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In this paper, we perform a comprehensive study for the physical propertiesof SN 2018gk which is a luminous type IIb supernova (SN). We find that theearly-time photospheric velocity vary from a larger value to a smaller valuebefore the photosphere reach a temperature floor. We generalize the photospheremodulus and fit the multi-band light curves (LCs) of SN 2018gk. We find thatthe $^{56}$Ni mass model require $\sim0.90$ M$_\odot$ of $^{56}$Ni which islarger than the derived ejecta mass ($\sim0.10$ M$_\odot$). Alternatively, weuse the magnetar plus $^{56}$Ni and the fallback plus $^{56}$Ni models to fitthe LCs of SN 2018gk, finding that the two models can fit the LCs. We favor themagnetar plus $^{56}$Ni since the parameters are rather reasonable ($M_{\rm ej}=1.65$ M$_\odot$, $M_{\rm Ni}=0.05$ M$_\odot$ which is smaller than the upperlimit of the value of the $^{56}$Ni mass can by synthesized by theneutrino-powered core collapse SNe $B=6.52\times10^{14}$ G which is comparableto those of luminous and superluminous SNe studied in the literature, and$P_0=10.42$ ms which is comparable to those of luminous SNe), while thevalidity of the fallback plus $^{56}$Ni model depends on the accretionefficiency ($\eta$). Therefore, we suggest that SN 2018gk might be a SN IIbmainly powered by a central engine. Finally, we confirm the NIR excesses of thespectral energy distributions (SEDs) of SN 2018gk at some epochs and constrainthe physical properties of the putative dust using the blackbody plus dustemission model.

SN 2018gk Revisited: the Photosphere, the Central Engine, And the Putative Dust